An Investigation of the Flow Characteristics and of Losses in Radial Nozzle Cascades

Abstract

A study was made of the flow in radial nozzle cascades using an air test rig and a water test rig. In the air test rig, three cobra probes were used in circumferential and spanwise traverses to determine the total pressure variations in the flow field at three radii downstream of the nozzles at which static pressure was also measured. The tests were made on two sets of nozzle blades having heights of 0.148 in. (0.376 cm) and 0.200 in. (0.508 cm), at trailing edge angles (measured from circumferential direction) of 15, 20, and 25 deg, and at two flow Mach numbers of approximately 0.2 and 0.35. The test results presented in this paper, in the form of loss coefficients and flow angles, were flow-weighted and averaged. Flow visualization in the air test rig was made on the walls bounding the nozzle blades using the graphite power-oil mixture technique. Additional tests were made on the water test rig using dye injection technique. Photographs were obtained showing clearly formation of secondary flow around each nozzle blade in the form of the leading edge vortex. The test results confirm the existence of the leading edge vortices reported peviously, and extend their study to the radial nozzle cascades.

LDV Measurements and Investigation of Flow Field Through Radial Turbine Guide Vanes

“…Large mixing effects were observed at the exit of the nozzle. Hashemi, Lemak and Owczarek [23] presented the results of total and static pressure measurements using conventional pressure probes at three radii downstream of radial nozzle cascades. They also conducted flow visualizations in the air and water test rigs.…”

Loss analysis of the shrouded radial-inflow turbine for compressed air energy storage

“…It should be pointed out that the losses in stator are not discussed because the stator is located at the upstream of shroud cavity, and there are little changes of the internal flow field in a favorable pressure gradient system. Early experimental investigations 30,31 showed that passage vortices know from axial turbines could not be found in the stator of radial turbine. Putra and Joos 32 argued that there exists an inflow vortex in the stator passage, which mainly causes the secondary vorticity in the circumferential direction.…”

Influence of the volute cross-sectional shape on mixed inflow turbine performances

“…Hashemi et al 7 conducted a study on a radial blades cascade, and their results in images showed just at leading edge the formation of the Horseshoe vortices, with a flow angle variation along the circumferential direction. They also noticed the appearance of these vortices which appear larger in size if the variation in incidence angle was important.…”